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Gamma-ray Bursts & SVOM Frédéric Daigne (Institut d’Astrophysique de Paris) + Robert Mochkovitch Journée scientifique Ondes Gravitationnelles – IAP – 27 janvier 2017 GRBs: observations Gamma-ray bursts: prompt emission Apparent rate: ~ 1 GRB / day ~ 10 s ~ 100 ms CGRO/BATSE Duration: two groups Lightcurves : variability & diversity Spectrum: non-thermal Beppo-SAX Gamma-ray bursts: afterglow Discovery: 1997 (X-rays: Beppo-SAX ; V: van Paradijs et al. 1997) Flux: power-law decay Non-thermal spectrum GRB970228 (Fruchter et al. 1999) Spectral evolution: X-rays → V → radio Follow-up: redshift & host galaxy High redshift (zmax,obs > 9): huge luminosity and radiative energy Eiso,g ~ 1051 – 1054 erg GRB 970508 : z = 0.835 (Metzger et al. 1997) Observed emission: prompt → afterglow Log Flux Prompt GRB (soft g-rays) Afterglow (X-rays) initial steep decay Swift XRT: Early steep decay: >90% Plateau: ~60% Flares: ~30% flares Plateau shallow decay : “normal” decay steeper decay : a = 2 - 3 Log Time Also: prompt optical, GeV Also: optical, radio afterglow GRB physics Log( R ) [meters] Cosmological distance: huge radiated energy (Eiso,g ~ 1050-1055 erg) Variability + energetics: violent formation of a stellar mass BH Long GRBs: collapse of a massive star Short GRBs: NS+NS/BH merger? (link with GW) Log( R ) [meters] Variability + energetics + gamma-ray spectrum: relativistic ejection Log( R ) [meters] Variability + energetics + gamma-ray spectrum: relativistic ejection Prompt emission: internal origin in the ejecta Log( R ) [meters] Variability + energetics + gamma-ray spectrum: relativistic ejection Prompt emission: internal origin in the ejecta Afterglow: deceleration by ambient medium Log( R ) [meters] Final state of massive stars Compact objects Relativistic ejecta Particle acceleration, non-thermal emission Non-photonic emission (GW ? Neutrinos ? CRs ?) Log( R ) [meters] GRB activities at IAP Modelling: prompt & afterglow emission (F. Daigne & R. Mochkovitch) - internal shock model (prompt phase) - photospheric emission - gamma-gamma annihilation, constraints on the Lorentz factor - long-lived reverse shock (afterglow phase) - comparison to Fermi data (collaboration with GSFC Washington: GBM & LUPM Montpellier: GBM/LAT) Shock acceleration, possible link with UHECRs (M. Lemoine) Population models, cosmic rates, link with SFR (F. Daigne J.Palmerio) Short GRB rates vs mergers/kilonovae (E. Vangioni, F. Daigne & collab.) Host galaxies (J. Palmerio with S. Vergani (GEPI & IAP) ; D. Leborgne) Afterglow spectroscopy (P. Petitjean & P. Noterdaeme) Shorts GRBs Merger scenario ? Indirect evidence = host galaxies Barthelmy et al. 2005 GRB 050724 @ VLT Short GRBs: no correlation with star formation good agreement with the merger scenario Long GRBs: star forming galaxies good agreement with the collapsar scenario A new challenge: short GRBs in the GW era First detection: GW150914 = BH+BH Advanced Ligo/Virgo: NS+NS NS+BH mergers are expected soon. Next step: electromagnetic counterparts? Final state of a merger Kilonova: NIR, V (days) Radio remnant (years) ~isotropic BUT weak q Short GRB: hard g-rays Bright BUT collimated r process OAG Detection rate: GW+GRB RGW GRB fg 1 ? q j2 RGW f g DC 2 4 qj = 0.1 – 0.3 ? source detector ≳ 8 sr (Fermi, GRM); 2 sr (Swift, Eclairs) DC (duty cycle) ≳ 50% RGW+GRB = 6 10-3 RGW (8 sr + “standard values” of fg, qj) What will be the observed rate RGW in O2, O3? In case of simultaneous detection: → confirmation of the link NS + NS/BH mergers and short GRBs → new measure of H0 if the burst redshift is known → delay GW – GRB : constraint on dissipation radius in GRBs Detection rate: GW+afterglow OAG Search of GW error box in X-rays, visible RGW AG q j2 RGW f g SE ( D, Ekin , n, delay/loc.) 2 Orphan afterglow: RGW OAG RGW f g SE ( D, Ekin , n, q obs , delay/loc.) At later times: kilonova (days) and radio remnant (years) remnant heated by radioactivity K R B V GRB 130603B Isotropic but weak… Tanvir et al. 2013 SVOM SVOM NAOC, Beijing IHEP, Beijing XIOPM, Xi’an SECM, Shanghai NSSC, Beijing CEA-Irfu, Saclay IRAP, Toulouse APC, Paris IAP, Paris LAM, Marseille LAL Orsay CPPM Marseille LUPM Montpellier GEPI Meudon Obs. Strasbourg U. of Leicester MPE, Garching CNES, Toulouse 21 SVOM in context q SVOM = Space-based multiband astronomical Variable Objects Monitor SVOM is a multi-wavelength Chinese-French mission dedicated to the transient sky. SVOM is a mission deployed on the ground and in space. The space segment of SVOM is planned to be launched early in the next decade (2021), for a 3 year nominal mission. SVOM is currently in phase C (budget accepted for phase D, E1 (post-launch) SVOM science: Core program: GRB physics + GRB as a tool for cosmology Multi-wavelength observation of transient phenomena Follow-up: GW, HE neutrinos, but also: radio, V/IR, HE gamma-rays (CTA) Observatory program See white paper SVOM at IAP: GRB science + contribution to the ground-segment (GRB pipeline) 3 co-Is: F. Daigne, R. Mochkovitch, P. Petitjean [M. Dennefeld ; M. Lemoine ; D. Leborgne ; P. Noterdaeme ; E. Vangioni] 2 engineers: L. Domisse (40%) + 3 years CDD UPMC (recruitment in progress) Satellite Payload MXT ~ 930 Kg ~ 450 kg 1 deg2, 0.2-10 keV, loc. < 1’ 262 arcmin2, visible, loc. < 2’’ VT ECLAIRs 2 sr, 4-150 keV, loc. < 13’ GRM 2x3 sr, 15 keV-5 MeV GFT-2 GWAC visible & NIR 5000 deg2 visible GFT-1 visible 24 A unique GRB sample GRB trigger ECLAIRs 42-80 GRBs/yr SVOM is sensitive to all classes of GRBs (long/short/soft/…) A unique GRB sample Prompt emission ECLAIRs+GRM Prompt GRB emission over 3 decades (4 keV-5.5 MeV) GWAC prompt visible emission in ~16% of cases The multi-component spectrum of the Fermi/GBM burst GRB 100724B simulated in ECLAIRs+GRM. A unique GRB sample Afterglow & distance slew request: 36-72 GRB/yr MXT X-ray afterglow (>90% of GRBs after a slew) VT Visible and NIR afterglow+photometric redshift GWAC C-GFT/F-GFT Very large telescopes Redshift in ~2/3 of cases The X-ray afterglow of the Swift burst GRB 091020 simulated in MXT. SVOM and the Gravitational Waves at the beginning of the next decade GW observations in 2020+ 2015 2019 2022 In 2020+ the network should be able to detect NS+NS/BH mergers within an error box of a few deg2. Expected NS-NS mergers detection rate: about 40/year within 445 Mpc (z~0.1) Expected BH-NS mergers detection rate: about 10/year within 927 Mpc (z~0.2) (Abadie et al. 2010: large uncertainties) SVOM launch: end of 2021 Conclusion (in two figures) How does (will) a GW +GRB association look like ? GW 150914 and GRB 150914 (Connaughton et al, 2016)